scyther/spdl/denning-sacco-shared.spdl

/*
* Denning-Sacco shared key
* CJ, but modeled after Sjouke's protocol list
*/

/* default includes */

/* asymmetric */

const pk,hash: Function;
secret sk,unhash: Function;

/* symmetric */

usertype SessionKey, Time, Ticket;
secret k: Function;

/* agents */

const a,b,e: Agent;


/* untrusted e */

untrusted e;
const ne: Nonce;
const kee: SessionKey;

compromised k(e,e);
compromised k(e,a);
compromised k(e,b);
compromised k(a,e);
compromised k(b,e);

protocol denningsaccosh(A,S,B)
{
	role A
	{
		var t: Time;
		var T: Ticket;
		var kab: SessionKey;

		send_1 (A,S, A,S );
		read_2 (S,A, {B, kab, t, T}k(A,S) );
		send_3 (A,B, T);

		claim_4 (A, Secret, kab);
		claim_5 (A, Nisynch);
		claim_6 (A, Niagree);
	}

	role S
	{
		const t: Time;
		const kab: SessionKey;

		read_1 (A,S, A,S );
		send_2 (S,A, {B, kab, t, { kab, A,t }k(B,S) }k(A,S) );
	}

	role B
	{
		var t: Time;
		var kab: SessionKey;

		read_3 (A,B, { kab, A,t }k(B,S) );

		claim_7 (B, Secret, kab);
		claim_8 (B, Nisynch);
		claim_9 (B, Niagree);
	}
}